Ongoing studies of experimental allergic encephalomyelitis (EAE) induced in laboratory animals will focus on: (1) role of cerebrovascular permeability in specific binding of cells and antibodies to the neuraxis of Lewis rats, relying on use of isotopically labelled rat gamma globulin and injected electron dense marker molecules, (2) prerequisites for regular induction of EAE in cats and hamsters (3)the nature of the factor(s) in lymphoid cells of sensitized donors responsible for EAE- transfer activity, and (4) further studies of the significance of perivascular fibrin in the neuraxis of rats developing EAE.